Planck 2013 Results. XXIV. Constraints on primordial non-Gaussianity
Collaboration
58 pages
Published in:
- Astron.Astrophys. 571 (2014) A24
- Published: Oct 29, 2014
e-Print:
- 1303.5084 [astro-ph.CO]
Report number:
- CERN-PH-TH-2013-137
Experiments:
Citations per year
Abstract: (arXiv)
The Planck nominal mission cosmic microwave background (CMB) maps yield unprecedented constraints on primordial non-Gaussianity (NG). Using three optimal bispectrum estimators, separable template-fitting (KSW), binned, and modal, we obtain consistent values for the primordial local, equilateral, and orthogonal bispectrum amplitudes, quoting as our final result fNL^local= 2.7+/-5.8, fNL^equil= -42+/-75, and fNL^ortho= -25+\-39 (68% CL statistical). NG is detected in the data; using skew-C_l statistics we find a nonzero bispectrum from residual point sources, and the ISW-lensing bispectrum at a level expected in the LambdaCDM scenario. The results are based on comprehensive cross-validation of these estimators on Gaussian and non-Gaussian simulations, are stable across component separation techniques, pass an extensive suite of tests, and are confirmed by skew-C_l, wavelet bispectrum and Minkowski functional estimators. Beyond estimates of individual shape amplitudes, we present model-independent, 3-dimensional reconstructions of the Planck CMB bispectrum and thus derive constraints on early-Universe scenarios that generate primordial NG, including general single-field models of inflation, excited initial states (non-Bunch-Davies vacua), and directionally-dependent vector models. We provide an initial survey of scale-dependent feature and resonance models. These results bound both general single-field and multi-field model parameter ranges, such as the speed of sound, c_s \geq 0.02 (95% CL), in an effective field theory parametrization, and the curvaton decay fraction r_D \geq 0.15 (95% CL). The Planck data significantly limit the viable parameter space of the ekpyrotic/cyclic scenarios. The amplitude of the 4-point function in the local model tauNL < 2800 (95% CL). These constraints represent the highest precision tests to date of physical mechanisms for the origin of cosmic structure.Note:
- 59 pages; LaTeX; 26 figures. This paper is one of a set associated with the 2013 data release from Planck. Updated version
- cosmology: cosmic background radiation
- cosmology: observations
- cosmology: theory
- cosmology: early Universe
- cosmology: inflation
- cosmic background radiation
- early Universe
- inflation
- methods: data analysis
- non-Gaussianity: primordial
References(274)
Figures(46)